a. Field of the Invention
The instant invention relates to body-surface mapping of at least a portion of a human torso, and more particularly to methods and systems for noninvasive electrophysiology study. In particular, the instant invention relates to a garment or vest comprising a plurality of electrodes that are preferably interconnected. The garment or vest may by used alone or in combination with a catheter or probe to calculate endocardial and epicardial voltages to map and/or treat the human heart.
b. Background Art
Imaging and diagnosing cardiac electrical activity can be problematic because the electrical activity is time dependent and spatially distributed throughout the myocardium. Electrocardiographic techniques that include, for example, electrocardiograms (ECG) and vectorcardiography (VCG) can be limited in their ability to provide information and/or data on regional electrocardiac activity. These methods can also fail to localize bioelectric events in the heart.
Simultaneous recordings of potentials at tens or hundreds of locations on the torso, for example, is known and can provide body surface potential maps (BSPMs) over the torso surface. Although the BSPMs can indicate regional cardiac electrical activity in a manner that may be different from conventional ECG techniques, the known BSPM techniques, on their own, may provide a comparatively low resolution, smoothed projection of cardiac electrical activity that does not facilitate visual detection or identification of cardiac event locations (e.g., sites of initiation of cardiac arrhythmias) and details of regional activity (e.g., number and location of arrythmogenic foci in the heart).
It is also common to measure the electrical potentials present on the interior surface of the heart as a part of an electrophysiological study of a patient's heart. Typically such measurements are used to form a two-dimensional map of the electrical activity of the heart muscle. An electrophysiologist will use the map, for example to locate centers of ectopic electrical activity occurring within the cardiac tissues. One traditional mapping technique involves a sequence of electrical measurements taken from mobile electrodes inserted into the heart chamber and placed in contact with the surface of the heart. An alternative mapping technique takes essentially simultaneous measurements from a floating electrode array to generate a two-dimensional map of electrical potentials.
The two-dimensional maps of the electrical potentials at the endocardial surface generated by these traditional processes may be less than ideal. Traditional systems have been limited in resolution by the number of electrodes used. The number of electrodes dictated the number of points for which the electrical activity of the endocardial surface could be mapped. Therefore, progress in endocardial mapping has involved either the introduction of progressively more electrodes on the mapping catheter or improved flexibility for moving a small mapping probe with electrodes from place to place on the endocardial surface. Direct contact with electrically active tissue is required by most systems in the prior art in order to obtain well conditioned electrical signals.
With an increasing use of nonpharmacological anti-arrhythmic interventions (e.g., ablation), comparatively rapid and accurate localization of electrocardiac events—both endocardial and body-surface—can be beneficial.